I recently aquired a 1985 BMW 318i. It will not idle properly. When
the engine is not in gear and in motion it will jump constantly between
900 and 1100 RPMs. Everything else seems to be running properly. I've
been told by some that the idle control unit needs to be replaced. Is
this likely? I have heard also that there is an idle control valve;
this is not the problem? I cannot locate the idle control unit.
Someone told me that it is between the glove box and dash, but I can't
find it. Will someone provide me with detailed instructions or a
diagram? I cannot afford a mechanic and am not savvy with cars. I
cannot afford a manual, but wonder whether or not this information is
provided in the Bentley manual.
If you cannot afford a manual you cannot afford $200 for a new idle
control unit, which is visible after removing the glovebox.
It is possible to disconnect this automatic idle feature entirely and
set a curb idle using the throttle cable adjustment, although starting
and warmup would then require holding the gas pedal down.
How do I disconnect the automatic idle feature? I removed the cover
between in-between the dash and glove box. I moved the hardware in and
out of position several times while looking for the idle control unit.
All of the sudden, the car started idling properly, steady at 600 or
700 RPMs. This is a coincidence? Or did I disconnect something by
mistake? I still have a problem? What do you think it is? I cannot
afford an extram $50 for a manual and thought that I could obtain an
ICU for $50 at pick-your-part yard.
All 318i's have this problem eventually, so used is not advised.
Maybe you have a wiring problem. The ICU is a small black box,
literally above the glovebox. See http://www.realoem.com/bmw/select.do
Now that I think about, disconnecting is a little involved. You must
block all flow thru the silver cylinder located engine top center. It
has a two-pin connector on the back. Remove the back hose, tape a penny
over the opening, and reassemble, leaving the connector off.
Having blocked this air valve, you must now adjust the throttle cable
to keep the throttle from fully closing. Turn the nut on the bracket
thru which the cable passes until the engines idles at about 750 RPM
when fully warm.
My thought is that if he couldn't afford the $50 or so (kinda high
if you ask me) and he isn't car savvy as he put it, why in the world
did he bother with an older car, much less a BMW.
That being said, first place I would've looked would have been a
vacuum leak (cracked hoses). I've found plenty of then on my sin's 87
325is and my 89 325i...
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